Experimental Study On Ch+ Formation From Doubly Charged Carbon And Molecular Hydrogen

We studied the reaction of doubly charged carbon C2+ (C iii) with molecular hydrogen, a possible source of the high, unexplained abundances of interstellar CH+. The experiment was carried out using the cryogenic linear 22-pole radio frequency ion trap. The measured reaction rate coefficient amounts to (1.5 0.2) x 10(-10) cm(3) s(-1), nearly independently of the covered temperature range from 15 to 300 K. In the product distribution study, the C+ ion was identified as the dominant product of the reaction. For the CH+ production, we determine an upper limit for the reaction rate coefficient at 2 x 10(-12) cm(3) s(-1).